Hill shading: controlling maximum darkness and lightness

We'd like to suggest some enhancements to user control of the shadow range in the hill shading interface.

There is already a control for shadow darkness, but we think it could be improved. The slider position corresponds to a value between dark and light: essentially you choose the darkest shade of grey that will appear in the hillshaded image. Good so far.

However, the control seems currently to operate as a threshold: all shadows darker than the chosen shade of grey are clipped to that shade. All detail in those darker shadows is therefore lost.

What we'd rather see is scaling of the available shadow values. So that after I set the shadow darkness to a certain grey, the darkest parts of the hill shade are given that value, and the surface is shaded continuously between that grey and the highlight value, without clipping and without loss of detail. (Or rather, since there is reduced contrast, the loss of detail is distributed uniformly through the shadow range.)

We'd also really like it if there could be a second slider (unless it could be combined with the first) which controlled the maximum lightness of highlights.

Together, the two shaders would define a range of shadow values applied continuously between the darkest and lightest areas of the shaded elevation model.

Does that make sense?

Tim

Comments

What you are saying does make sense. I have updated the hill shading when a non-zero maximum shadow darkness is used to scale the shadows between the maximum brightness and darkness rather than clamping any shadows to the max darkness value. This should provide more detail while still obeying the darkness value.